The invention pertains to electro-mechanical relays of the type which alternately allow current to flow through one of two or more circuits.
One way to close a circuit connection is by way of an electro-mechanical relay. In its simplest form, a relay merely makes or breaks a single circuit connection (i.e., it opens or closes a path through which current may flow). Depending on the relay""s intended use, a biased conductor which makes the circuit connection is biased so that the connection is xe2x80x9cnormally openxe2x80x9d or xe2x80x9cnormally closedxe2x80x9d. An armature which is movable between first and second positions then presses on the biased conductor when the armature is moved to one of its positions, and the pressing on the biased conductor causes the biased conductor to move from its biased state. In this manner, a normally open connection may be closed, and a normally closed connection may be opened. Movement of the armature is controlled by an electro-magnetic actuator assembly. Typically, the actuator assembly will comprise a magnetic core encircled by an electric coil. The ends of the coil are coupled to a control circuit. When the control circuit is closed, current flows through the coil and causes the magnetic core to exert an attractive or repelling force which causes a relay""s armature to move out of its biased position. When the control circuit is opened, current ceases to flow through the coil and the magnetic force exerted by the core ceases to exist. Opening the control circuit therefore allows a relay""s armature to return to its biased position. While the movement of an armature is typically rotational (e.g., the armature is mounted within a relay using pins which lie on the armature""s rotational axis), the movement of an armature is sometimes translational (e.g., the armature is mounted so that it travels along a track).
While some simple relays comprise only a single circuit, and therefore a single current path which may be opened or closed, other relays comprise two or more circuits through which current may alternately flow, depending on which of the two or more circuits is currently closed. In some relays, two alternate circuit paths will comprise a pass-through circuit path and an attenuated circuit path. The pass-through circuit path simply allows electrical signals to flow through the relay without attenuation. On the other hand, and as its name implies, the attenuated circuit path attenuates electrical signals which flow through the relay.
With advances in manufacturing technology, electronic devices have become increasingly smaller. As a result, the size of electro-mechanical relays has decreased. However, as pass-through and attenuator circuits are mounted in closer proximity of one another, there is a greater chance that the two circuits will interfere with one another. For example, an electrical signal flowing through an attenuator circuit may receive unwanted attenuation from an open pass-through circuit or vice versa. The open circuit acts as an antenna which receives stray electrical signals and then capacitively transfers the stray signals to the closed circuit. Because this interference may increase as the distance separating the relevant circuits decreases, reducing this interference to a manageable level has become an increasingly important design criterion for miniature relays.
An example of a typical electro-mechanical relay comprising pass-through and attenuator circuits, which is hereby incorporated by reference for all that it discloses, is disclosed in the U.S. Patent of Blair et al. entitled xe2x80x9cAttenuator Relayxe2x80x9d (U.S. Pat. No. 5,315,273). The relay disclosed by Blair et al. is intended to be housed in a cannister having a volume of approximately 0.05 cubic inches. While such a miniature relay is adequate for some applications, the close proximity of its pass-through and attenuator circuits results in too much noise in other applications.
Consequently, a need exists for an electro-mechanical relay that is capable of alternately opening and closing two or more circuits (e.g., pass-through and attenuator circuits) such that an open one of the circuits does not impart noise to a closed one of the circuits.
In achievement of the foregoing need, the inventor has devised a new electro-mechanical relay.
In one embodiment of the invention, a relay comprises a substrate, a first circuit mounted on a first face of the substrate, a second circuit mounted on a second face of the substrate, an electro-magnetic actuator assembly, and an armature assembly which is movable between first and second positions with respect to the substrate. Movement of the armature assembly is controlled by the electro-magnetic actuator assembly, and when the armature assembly is moved to its first position, current is allowed to flow through the first circuit. When the armature assembly is moved to its second position, current is allowed to flow through the second circuit. Use of the substrate to separate the two circuits ensures that interference between the two circuits is kept below an adequate level.
The armature assembly can open and close the two circuits in a number of ways. In one relay which is described herein, an armature assembly comprises a number of actuator arms, some of which pass through the substrate. Actuator arms which do and do not pass through the substrate press on a number of spring clips and/or other biased conductors to open and/or close circuits. In another relay described herein, an armature assembly is mounted so that it presses on at least one biased conductor which abuts a substrate. The biased conductor comprises contacts which are suspended both above and below the substrate such that movement of the biased conductor enables it to alternately make contact with a circuit mounted on either of two faces of a substrate.
In some embodiments of the invention, a relay""s armature assembly is provided with actuator arms which are used to couple a circuit which is not in use to ground. In this manner, it is even more unlikely that a relay""s open circuit(s) will interfere with a relay""s closed circuit.